#include<assert.h>

namespace bit
{
	class string
	{
	public:
		typedef char* iterator;
		typedef const char* const_iterator;

		iterator begin()
		{
			return _str;
		}

		iterator end()
		{
			return _str + _size;
		}

		const_iterator begin()const
		{
			return _str;
		}

		const_iterator end()cosnt
		{
			return _str + _size;
		}

		/*string()
			:_str(new char[1] {'\0'})
			, _size;
			, _capacity;
			{}*/

		string(const char* str = "")
			:_size(strlen(str))
			, _capacity(_size)
		{
			_str = new char[_capacity + 1];
			strcpy(_str, str);
		}

		~string()
		{
			delete[] _str;
			_str = nullptr;
			_size = _capacity = 0;
		}

		char& operator[](size_t pos)
		{
			assert(pos < _size);

			return _str[pos];
		}

		const char& operator[](size_t pos)
		{
			assert(pos < _size);

			return _str[pos];
		}

		const char& operator[](size_t pos)const
		{
			assert(pos < _size);

			return _str[pos];
		}

		size_t capacity()const
		{
			return _capacity;
		}

		size_t size()const
		{
			return _size;
		}

		const char* C_str()const
		{
			return _str;
		}

		void reserve(size_t n)
		{
			if (n > _capacity)
			{
				char* tmp = new char[n + 1];
				strcpy(tmp, _str);
				delete[]_str;
				_str = tmp;

				_capacity = n;
			}
		}

		void Push_back(char ch)
		{
			if (_size == _capacity)
			{
				reverse(_capacity == 0 ? 4_capacity * 2);
			}

			_str[_size] = ch;
			++_size;
			_str[_size] = '\0';
		}

		void append(const char* str)
		{
			size_t len = strlen(str);
			if (_size + len > _capcity)
			{
				reserve(_size + len);
			}

			strcpy(_str + _size, str);
			_size += len;
		}

		string& operator+=(char ch)
		{
			push_back(ch);
			return *this;
		}

		string& operator+=(const char* str)
		{
			append(str);	
			return *this;
		}

		//insert(0,'x)
		void insert(size_t pos, char ch)
		{
			assert(pos <= _size);
			if (_size == _capacity)
			{
				reserve(_capacity == 0 ? 4 : _capacity * 2);
			}

			size_t end = _size + 1;
			while (end > pos)
			{
				_str[end] = _str[end - 1];
				--end;
			}

			_str[pos] = ch;
			_size++;
		}

		void insert(size_t pos,const char* str)
		{}

		void erase(size_t pos,size_t len=npos)
		{}

		bool operator<(cosnt string& s)const
		{
			return strcmp(_str, s._str) < 0;
		}

		bool operator==(const string& s)const
		{
			return strcmp(_str, s.s_str) == 0;
		}

		bool operator<=(const string& s)const
		{
			return *this < s || *this == s;
		}

		bool operator>(const string& s)const
		{
			return !(*this < s);
		}

		bool operator>=(const string& s)const
		{
			return !(*this < s);
		}

		bool operator!=(const string& s)const
		{
			return !(*this == s);
		}

		void clear()
		{
			_str[0] = '\0';
			_size = 0;
		}
		private:
			char* _str;
			size_t _size;
			size_t capacity;
			const static size_t npos;
	};
}